v2.1.0 — Real-time collaboration, performance & security overhaul

Real-Time Collaboration (WebSocket):
- WebSocket server with JWT auth and trip-based rooms
- Live sync for all CRUD operations (places, assignments, days, notes, budget, packing, reservations, files)
- Socket-based exclusion to prevent duplicate updates
- Auto-reconnect with exponential backoff
- Assignment move sync between days

Performance:
- 16 database indexes on all foreign key columns
- N+1 query fix in places, assignments and days endpoints
- Marker clustering (react-leaflet-cluster) with configurable radius
- List virtualization (react-window) for places sidebar
- useMemo for filtered places
- SQLite WAL mode + busy_timeout for concurrent writes
- Weather API: server-side cache (1h forecast, 15min current) + client sessionStorage
- Google Places photos: persisted to DB after first fetch
- Google Details: 3-tier cache (memory → sessionStorage → API)

Security:
- CORS auto-configuration (production: same-origin, dev: open)
- API keys removed from /auth/me response
- Admin-only endpoint for reading API keys
- Path traversal prevention in cover image deletion
- JWT secret persisted to file (survives restarts)
- Avatar upload file extension whitelist
- API key fallback: normal users use admin's key without exposure
- Case-insensitive email login

Dark Mode:
- Fixed hardcoded colors across PackingList, Budget, ReservationModal, ReservationsPanel
- Mobile map buttons and sidebar sheets respect dark mode
- Cluster markers always dark

UI/UX:
- Redesigned login page with animated planes, stars and feature cards
- Admin: create user functionality with CustomSelect
- Mobile: day-picker popup for assigning places to days
- Mobile: touch-friendly reorder buttons (32px targets)
- Mobile: responsive text (shorter labels on small screens)
- Packing list: index-based category colors
- i18n: translated date picker placeholder, fixed German labels
- Default map tile: CartoDB Light

client/src/components/Planner/DayPlanSidebar.jsx

@@ -661,7 +661,7 @@ export default function DayPlanSidebar({
                                 </div>
                               )}
                             </div>
-                            <div style={{ flexShrink: 0, display: 'flex', flexDirection: 'column', gap: 1, opacity: isHovered ? 1 : 0, transition: 'opacity 0.15s' }}>
+                            <div className="reorder-buttons" style={{ flexShrink: 0, display: 'flex', gap: 1, opacity: isHovered ? 1 : undefined, transition: 'opacity 0.15s' }}>
                               <button onClick={moveUp} disabled={placeIdx === 0} style={{ background: 'none', border: 'none', padding: '1px 2px', cursor: placeIdx === 0 ? 'default' : 'pointer', color: placeIdx === 0 ? 'var(--border-primary)' : 'var(--text-faint)', display: 'flex', lineHeight: 1 }}>
                                 <ChevronUp size={12} strokeWidth={2} />
                               </button>
@@ -736,14 +736,14 @@ export default function DayPlanSidebar({
                               <div style={{ fontSize: 10.5, fontWeight: 400, color: 'var(--text-faint)', lineHeight: '1.2', marginTop: 2 }}>{note.time}</div>
                             )}
                           </div>
-                          <div style={{ flexShrink: 0, display: 'flex', flexDirection: 'column', gap: 1, opacity: isNoteHovered ? 1 : 0, transition: 'opacity 0.15s' }}>
-                            <button onClick={e => { e.stopPropagation(); moveNote(day.id, note.id, 'up') }} disabled={noteIdx === 0} style={{ background: 'none', border: 'none', padding: '1px 2px', cursor: noteIdx === 0 ? 'default' : 'pointer', color: noteIdx === 0 ? 'var(--border-primary)' : 'var(--text-faint)', display: 'flex', lineHeight: 1 }}><ChevronUp size={12} strokeWidth={2} /></button>
-                            <button onClick={e => { e.stopPropagation(); moveNote(day.id, note.id, 'down') }} disabled={noteIdx === merged.length - 1} style={{ background: 'none', border: 'none', padding: '1px 2px', cursor: noteIdx === merged.length - 1 ? 'default' : 'pointer', color: noteIdx === merged.length - 1 ? 'var(--border-primary)' : 'var(--text-faint)', display: 'flex', lineHeight: 1 }}><ChevronDown size={12} strokeWidth={2} /></button>
-                          </div>
-                          <div style={{ display: 'flex', gap: 1, flexShrink: 0, opacity: isNoteHovered ? 1 : 0, transition: 'opacity 0.15s' }}>
+                          <div className="note-edit-buttons" style={{ display: 'flex', gap: 1, flexShrink: 0, opacity: isNoteHovered ? 1 : 0, transition: 'opacity 0.15s' }}>
                             <button onClick={e => openEditNote(day.id, note, e)} style={{ background: 'none', border: 'none', padding: 2, cursor: 'pointer', color: 'var(--text-faint)', display: 'flex' }}><Pencil size={10} /></button>
                             <button onClick={e => deleteNote(day.id, note.id, e)} style={{ background: 'none', border: 'none', padding: 2, cursor: 'pointer', color: 'var(--text-faint)', display: 'flex' }}><Trash2 size={10} /></button>
                           </div>
+                          <div className="reorder-buttons" style={{ flexShrink: 0, display: 'flex', gap: 1, opacity: isNoteHovered ? 1 : undefined, transition: 'opacity 0.15s' }}>
+                            <button onClick={e => { e.stopPropagation(); moveNote(day.id, note.id, 'up') }} disabled={noteIdx === 0} style={{ background: 'none', border: 'none', padding: '1px 2px', cursor: noteIdx === 0 ? 'default' : 'pointer', color: noteIdx === 0 ? 'var(--border-primary)' : 'var(--text-faint)', display: 'flex', lineHeight: 1 }}><ChevronUp size={12} strokeWidth={2} /></button>
+                            <button onClick={e => { e.stopPropagation(); moveNote(day.id, note.id, 'down') }} disabled={noteIdx === merged.length - 1} style={{ background: 'none', border: 'none', padding: '1px 2px', cursor: noteIdx === merged.length - 1 ? 'default' : 'pointer', color: noteIdx === merged.length - 1 ? 'var(--border-primary)' : 'var(--text-faint)', display: 'flex', lineHeight: 1 }}><ChevronDown size={12} strokeWidth={2} /></button>
+                          </div>
                         </div>
                         </React.Fragment>
                       )